Microsoft has finally provided a few more details on Windows Phone 7.8, the update designed to appease Windows Phone 7 device owners who won’t receive an upgrade to Windows Phone 8. However, although the news confirms it’s still being worked on, there’s no exact launch date.

Windows Phone 7.8 was announced alongside Windows Phone 8 in June, but when the new software was released at the end of October and Microsoft did not mention it at all, we questioned what was going on. Microsoft promised new information “in the coming weeks,” and here we are.

Terry Myerson, Corporate Vice President of Windows Phone, has now covered the topic on the official Windows Phone Blog. We already know WP7.8 will bring the new Start screen to older devices, but now we also know it will feature new themes and 20 different accent colors, plus the chance to make the Bing Picture of the Day your lock screen image. Microsoft has also provided some extra security with a new passcode system.

If you’ve been following the Windows Phone 7.8 story, then you’ll recognize most of these features from a late-October leak, but there has been no confirmation of Xbox Music, SmartGlass or the possibly Lumia-specific Bluetooth media transfer feature.

So when is it coming? If you’re heading out to buy a new Windows Phone 7 device, which Nokia still produces, then in the near future it should come with Windows Phone 7.8 already installed. Myerson explains that these cheaper devices are “incredibly important for broadening the reach of Windows Phone across the globe.”

As for the update, it’s not coming until “early 2013,” confirming Microsoft’s split strategy rumored in mid-November. So, that’s a five month wait between announcement and now, plus at least another month until it’s even slightly likely to appear. The post says it’s working with networks and hardware partners to get the update approved, so it can be on as many devices as possible early next year. How early is early? Only Microsoft knows, but with the Apollo Plus Windows Phone 8 update rumored to be up for discussion at Mobile World Congress 2013 — which begins on February 25 — it’s logical to expect more information then.